Gear Oil

[cplanner]

Have been checking the treads on this subjuct and now have a question on gear oil. Either going with the Moooooooopar 75w140 or the Royal Purple 75w140. Myag-Hytec differential cover on its way from Geno's. Does the 75w140 have to be replaced with 75w90 when winter comes? Live in Ohio and not really sure what I need to do. Pull a 5er most of the year but when winter gets here mainly used for back and forth to work. Not as much towing.

 

[jnelson]

I have ran both 75w-140 and 75w-90 down here in S. Texas where it gets pretty darn hot. I ran Mobil 1 75w-90 and I curently use 75w140 Amsoil. I probobly put 250,000 miles on my truck with 75-90 in the diff. I also put the friction modifier in also.

 

[George D]

Just put Royal Purple 75-140 in the rear. Did not need friction modifier, LSD does fine without it. Should be good for year round regardless of temp. Also put Synchromax in transfer case and trans.

 

[Extreme1]

Read your owner's manual for confirmation but I think the 75w-140 is the recommendation for towing and the 75w-90 is for not towing. Either one will work in cold temps because the cold temp viscosity is the same (75).